Refrigerating system with air control means



Feb. 4,1969 w, STREED ETAL 3,425,235

REFRIGERATING SYSTEM WITH AIRYCONTROL MEANS Filed Feb. 21, 1967 M'l/iom 25 $2221 BY Beaucbamp A/o/iu M, M W

Affamgga United States Patent 3,425,236 REFRIGERATING SYSTEgTSWITH AIR CONTROL ME William R. Streed and Beauchamp Nolin, Montgomery, Ala., assignors to Nolin Manufacturing Company, Inc., a corporation of Alabama Filed Feb. 21, 1967, Ser. No. 617,611 US. Cl. 62-140 Int. Cl. F25d 21/02, 17/06; A47f 3/04 3 Claims ABSTRACT OF THE DISCLOSURE Heretofore in the art to which our invention relates, it has been the usual practice to cool frozen food products, such as frozen foods displayed in cases in grocery stores and the like by circulating air from a cooling unit in heat transfer relation to the area to be cooled and then returning the air to the cooling unit. The amount of air circulated adjacent the area to be cooled has heretobefore been controlled by varying the number of fan or blower units employed to circulate the air. It has also been the usual practice to circulate the air continuously over the food products during the defrost cycle as well as during the cooling cycle. It is very desirable to control the amount of air which passes over the product to be cooled due to the fact that too much air over the product load will spill over the case and cause loss of refrigeration. On the other hand, too little air supplied to the area to be cooled will not promote the required cooling whereby the temperature rises in the product area. Also, where the warm moist air circulated during the defrosting cycle passes over the product, condensation takes place whereby frost builds up on the product to the extent that it is even difficult to determine what product is in the packages being cooled.

In accordance with our present invention, we control the amount of air introduced into and adjacent the area to be cooled by by-passing excess air directly to the return side of the cooling unit whereby suflicient air is always supplied to the area to be cooled without any spill-over and at the same time the efiiciency of the refrigerating unit is greatly increased. During the defrosting cycle. we by-pass all of the air directly to the return side of the cooling unit whereby there is no circulation of the warm, moist air over the product load during defrost.

A further object of our invention is tov provide a refrigerating system in which a shorter defrost cycle is required due to the movement of the Warm air over the entire coil surfaces and the washing effect of the moist, warm air.

A further object of our invention is to provide'a refrigerating system of the character designated in which the ice overall efficiency of the system is increased by providing an insulated partition between the by-pass passageway and the area to be cooled.

A still further object of our invention is to provide a refrigerating system of the character designated which shall be economical of manufacture and one in which the air entering the cooling unit is at a minimum temperature at all times, thus reducing the compressor load and increasing the efficiency of the system Apparatus embodying features of our invention is illustrated in the accompanying drawing forming a part of this application, in which:

FIG. 1 is a vertical sectional view through a display case for frozen food products and embodying our improved refrigerating system;

FIG. 2 is an enlarged, fragmental view of the air control mechanism;

FIG. 3 is an enlarged, fragmental view showing one means for commencing the defrosting cycle; and,

FIG. 4 is a diagrammatic wiring diagram.

Referring now to the drawing for a better understand ing of our invention, we show a case 10 which is formed of a suitable insulating material whereby there is a minimum heat loss to the surrounding area. The products to be cooled, such as frozen food packages 11, are supported in an upwardly opening chamber 12 having a bottom wall 13 formed of an insulating material, as shown in FIG. 1.

The upwardly opening chamber 12 is supported in spaced relation to the inner surface of the case 10, as shown. Mounted adjacent and in vertically spaced relation below the bottom wall 13 of the chamber 12 is a cooling unit indicated generally at 14 which may comprise the usual coils 16. Wall 17 extends alongside the upper surface of the cooling unit 16, as shown in FIG. 1, to define a passageway 18 between the under surface of the wall 13 and the upper surface of wall 17.

A fan or blower housing 19 is provided in the wall 17 for receiving a fan unit 21 which forces air into the receiving end of the cooling unit 14. The air leaving the discharge end of the cooling unit 14 passes upwardly through a passageway 22 located between the chamber 12 and the side of the case 10. The cooling air then passes through a grill 23 whereupon it passes over and across the upper surface of the packages 11 to be cooled. The air then enters a grill 24 whereupon it passes downwardly through a passageway 26 and then through the blower housing 19 to the receiving side of the cooling unit 14.

The wall 17 is provided with an upwardly extending portion 27 which is provided with a plurality of passageways 28 therethrough for receiving air discharged from the cooling unit 14. Preferably, the wall 17 and the upstanding portion 27 thereof extend the length of the case 10.

Mounted for pivotal movement on a supporting shaft 29 is a baffle 31 which is adapted to move from the solid line position shown in FIG. 1 and 2 to the dotted line positions. A bracket 32 carried by the baffle 31 is pivotal ly connected by a pin 33 to one end of a horizontal bracket 34 which in turn is connected to a tension spring 36. The other end of the tension springis connected to the armature 37 of an electrical solenoid 38. Upon energizing the solenoid 38, the baffle 31 moves from the solid line position to the dotted line position to thus prevent the passage of air upwardly through the passageway 22 to the area to be cooled. Accordingly, all of the air is deflected into the passageway 18 while the bafile 31 is in the dotted line position shown in FIGS. 1 and 2. The air passing through the passageway 18 is then returned through the fan housing 19 directly to the receiving end of the cooling unit 14. When the solenoid 38 is deenergized, a spring 39 returns the baffle 31 to the solid position shown in FIGS. 1 and 2. The spring 39 is mounted between the solenoid housing and a spring abutment 41, as shown.

With the baffle 31 in the solid line position shown in FIGS. 1 and 2, the air leaving the discharge end of the cooling unit 14 passes upwardly whereby a portion passes through the passageway 22 and the remainder passes through the openings 28 in the vertical wall 27. The baffle 31 is held in adjusted position relative to the vertical wall 27 by an adjusting screw 42 which is held in selected postions by lock nuts 43. By adjusting the position of the baffle 31, the amount of air passing upwardly through the passageway 22 and across the upper surface of the packages 11 may be controlled to prevent the introduction of excess air which would spill over and thus waste refrigeration. Also, the baffle 31 may be adjusted to a proper location to introduce suflicient air into the area to be cooled to maintain the cooled area at the desired temperature.

To aid in defrosting the cooling unit 14, we provide a heating unit 44 adjacent the receiving end of the cooling unit 14 whereby the air is heated prior to entering the cooling unit 14 during the defrost cycle. The solenoid 38 and the heating unit 44 are in circuit with a solenoid 46 that controls a valve 47 which supplies refrigerant gas to the coils 16 of the refrigerating unit in a manner well understood in the art. The heating element 44 and solenoids 38 and 46 are also in circuit with a relay 48 which closes a switch 49 to start the defrost cycle. The relay 48 .is actuated by a diaphragm switch unit indicated generally at 51 which is actuated upon a predetermined build up of pressure within a conduit 52. As shown in FIG. 1, ,the conduit 52 has a branch conduit 53 which terminates at the fan housing 19 whereby air is forced through the tube 53 into tube 52. The end of tube 52 carries a sensing element 54 which is mounted adjacent one of the cooling coils 16, as shown in FIG. 3. So long as the space between the sensing element 54 and the coil 16 is unobstructed, the switch 49 remains open. On the other hand, upon a build up of ice between the sensing element 54 and the coil 16, there would be a build of pressure within the conduit 52 whereupon the diaphragm switch 51 would be actuated to energize relay 48 and thus close switch 49 to complete the circuit to the heating element 44 and the solenoids 38 and 46 to start the defrost cycle. The diaphragm switch 51 is provided with a thermostatic switch and a thermostat bulb 56, as shown in FIG. 4 whereby upon a predetermined increase in temperature adjacent the bulb 56, the relay 48 is deenergized to thus open the switch 49 and thus start the cooling cycle.

From the foregoing description, the operation of our improved refrigerating system will be readily understood. The adjusting screw 42 is adjusted to position the baffle 31 in a proper relation to the vertical wall 27 whereby the required amount of air is circulated upwardly through the passageway 22 to the area to be cooled. Excess air is conveyed through the passageway 18 and fan housing 19 to the return side of the cooling unit 14. As the cooling air leaves the cooling unit 14, it is preferably at a temperature of approximately 38" F. At the time the cooling air enters the area to be cooled, the temperature is approximately 28 'F. The air is then returned to the grill 24 at a temperature of approximately 18 F. The air which passes through the by-pass passageway 18 reaches a temperature of approximately 32 F, at the time it enters fan housing 19. Accordingly, the 32" F. air

mixes with the 18 F. air to thus introduce air at approximately 28 F. into the receiving end of cooling unit 14.

The refrigerating system'operates on the cooling cycle until there is a build up of ice between the sensing member 54 and coil 16. At this time the relay switch 49 is closed whereupon the circuit is completed to the heating unit 44 and solenoids 38 and 46 to thus cut off the gas supply to the coils 16 and at the same time move the bafile 31 to the dotted line position shown in FIGS. 1 and 2. With the baffle 31 closing off the passageway 22, all of the air passes directly through the by-pass 18 into the fan housing 19 and is then returned past the heating element 44 into the receiving end of the cooling unit 14 to defrost the coils 16. The moist, heated air is thus recirculated relative to the coils 16 without passing into the area to be cooled adjacent the packages 11. Upon a predetermined increase in temperature within the cooling unit 14 adjacent the bulb 56, the diaphragm switch 51 is actuated to thus deenergize the relay 48 whereby the switch 49 moves to open position to break the circuit to the heating unit 44 and the solenoids 38 and 46 whereupon the bafile 31 returns to the solid line position and the refrigerant gas is again supplied to the coils 16 to start the cooling cycle.

From the foregoing it will be seen that we have devised an improved refrigerating system. By regulating the flow of cooling air whereby the exact required amount of cooling air is introduced into the cooling area to maintain the desired temperature therein and at the same time prevent overflow, there is no waste of refrigeration. Also, by recirculating all the excess cooling air directly to the receiving end of the cooling unit, we greatly increase the efficiency of operation of the system. Furthermore, by moving the bafile 31 to the dotted line position, shown in FIGS. 1 and 2 at the beginning of the defrost cycle, all of the warm, moist air by-passes the area to be cooled whereby the moist, warm air is recirculated continuously relative to the coils 1-6 whereupon they are defrosted in a minimum of time and at the same time, the moist, warm air does not condense onto the surface of the articles 11 being cooled in the chamber 12.

While we have shown the sensing device 54 as being in the form of a device which is actuated upon a predetermined build up of ice on the coil 16, it will be apparent that our improved apparatus may be also actuated by a time clock or the like.

We claim:

1. In a refrigerating system having cooling cycle, a defrost cycle, a cooling unit, an area to be cooled and means for circulating air in heat transfer relation to the cooling unit and the area to be cooled with the air passing from a discharge side of the cooling unit to the area to be cooled and then back to a receiving side of the cooling unit, the improvement which comprises:

(a) there being an air by-pass adjacent the discharge side of the cooling unit communicating the means for circulating air adjacent said discharge side of the cooling unit directly with the means for circulating air adjacent said receiving side of the cooling unit,

(b) an air control member movable to a first position to direct the flow of all air through said by-pass during the defrost cycle so that air by-passes the area to be cooled during the defrost cycle and to a second position to permit at least partial air flow to said area to be cooled and through said by-pass during the cooling cycle, and

(c) means to hold said air control member at selected positions during the cooling cycle to vary the amount of air which passes through said bypass and the amount of air which passes to the area to be cooled.

2. In a refrigerating system as defined in claim 1 in which the cooling unit is separated from the area to be cooled by an insulated partition which defines said bypass between said partition and the cooling unit and a perforated wall is provided between said partition and 6 said cooling unit adjacent said discharge side of the References Cited cooling unit and said air control unit comprises a mo UNITED STATES PATENTS able baffle mounted in position to control the flow of air to the area to be cooled and the flow of air through said 2,810,267 10/1957 Rafter 62275 XR perforated wall into said by-pass. 5 2,960,844 11/1960 Qulck 62275 XR 3. In a refrigerating system as defined in claim 2 in 3,050,956 8/1962 Mann 62 275 which an adjustable member is carried by said perforated wall in position to retain said movable baffle at selected MEYER PERLIN Pnmary Exammer' positions relative to said perforated wall to vary the US Cl XR amount of air which flows through the perforated wall 10 into said by pass I 

